Merge pull request #23 from tendermint/hexfuncs

IsHex and StripHex

common/string.go

@@ -1,12 +1,15 @@
 package common
 
 import (
+	"encoding/hex"
 	"fmt"
 	"strings"
 )
 
+// Fmt shorthand, XXX DEPRECATED
 var Fmt = fmt.Sprintf
 
+// RightPadString adds spaces to the right of a string to make it length totalLength
 func RightPadString(s string, totalLength int) string {
 	remaining := totalLength - len(s)
 	if remaining > 0 {
@@ -15,6 +18,7 @@ func RightPadString(s string, totalLength int) string {
 	return s
 }
 
+// LeftPadString adds spaces to the left of a string to make it length totalLength
 func LeftPadString(s string, totalLength int) string {
 	remaining := totalLength - len(s)
 	if remaining > 0 {
@@ -22,3 +26,23 @@ func LeftPadString(s string, totalLength int) string {
 	}
 	return s
 }
+
+// IsHex returns true for non-empty hex-string prefixed with "0x"
+func IsHex(s string) bool {
+	if len(s) > 2 && s[:2] == "0x" {
+		_, err := hex.DecodeString(s[2:])
+		if err != nil {
+			return false
+		}
+		return true
+	}
+	return false
+}
+
+// StripHex returns hex string without leading "0x"
+func StripHex(s string) string {
+	if IsHex(s) {
+		return s[2:]
+	}
+	return s
+}